Cleaning machines of the type wherein a washing liquid is fed from a receptacle to a surface to be washed and then, by means of suction, is returned to the original receptacle for further use, preferably after being filtered, are known. Often these units include a tank-like receptacle that houses a pump for dispensing the cleaning liquid, a suction fan for returning the liquid, and a filtering means, while also providing the storage facility for the cleaning liquid. The tank-like receptacle is designed to sit on the floor and flexible liquid discharge and liquid return hoses connect the tank-like receptacle with a cleaning head used to apply and retrieve the cleaning liquid from the surface being cleaned.
While devices of the aforementioned type are portable, they are anything but compact and lightweight, particularly when their cleaning fluid tank is full. Furthermore, the presence in such apparatus of a separate tank that must rest on the floor not only makes use of the apparatus cumbersome, but is restrictive with respect to the places that such a unit can be effectively utilized. For example, long flights of steps having no landing upon which the tank can rest can render the apparatus unusable. Furthermore, because of the cumbersome nature of such units, it is often impractical to utilize the unit for spot cleaning purposes, such as cleaning up a small spill, as opposed to general room cleaning.
As a result, it is desirable to have a cleaning apparatus wherein all of the operative components are mounted upon a common element so that the unit is unencumbered by a separate floor-supported tank. In view of this, floor cleaning devices have been configured to be similar to an upright vacuum cleaner or so-called electric broom, and have all of the operative components for spraying a cleaning fluid onto a floor surface, such as a carpet, and for using suction to collect the dirty cleaning liquid, as well as a means for storing the fluid that is applied and collected mounted upon a common element. The versatility of such "common element" type cleaning apparatus is severely restricted to floor-type uses because these units are too large and heavy to be used in a manner that is unsupported by contact with the floor surface to be cleaned and because the units are not designed for operation in orientations that would be necessary for cleaning vertical surfaces.
To overcome these disadvantages, relatively small, light-weight, portable handheld cleaning units have been developed which apply cleaning fluid to a surface area that can be cleaned with a single application of a limited quantity of cleaning fluid carried by the unit. U.S. Pat. Nos. 4,788,738 and 4,930,178 to Monson et al. and 4,536,914 and 4,542,557 to Levine shown cleaners of this type.
A problem encountered with previous handheld cleaning units is to effectively separate fluid from air within the unit when the fluid-air mixture is extracted from a surface to be cleaned. In a cleaning unit having the capability of providing a high suction force for effective cleaning, fluid entrained in air tends to be drawn into the vacuum blower for the unit and could ultimately result in damage to the vacuum blower.
Also, existing hand held extraction cleaners generally recycle dirty fluid into the same receptacle which contained the clean fluid originally applied to the surface to be cleaned. For many applications, this is unsatisfactory for recycled fluid can be contaminated or dirty enough to add to a stain to be cleaned. This is particularly true when the internal fluid paths within a cleaner become dirty or contaminated, for previous hand held cleaners provided no means for flushing these internal fluid paths.
Finally, previous hand held fluid extraction cleaners were not suitable for use in removing contaminants, such as spilled blood or other contaminated fluids, as the cleaner would remain contaminated after a single use.